http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
DC-AC 펄스 탄뎀 GMA 용접에서 공정변수에 따른 스패터 발생 거동에 대한 연구
강상훈(Sanghoon Kang),방희선(Hee-seon Bang),김철희(Cheolhee Kim) 대한용접·접합학회 2018 대한용접·접합학회지 Vol.36 No.3
High deposition is required to improve welding efficiency in the thick plate welding. Tandem gas metal arc(GMA) welding has been introduced for high deposition and synchronized DC pulse welding system is usually employed to avoid the electro-magnetic interruption between two adjacent arcs. In this study, constant voltage DC welding for leading arc and AC pulse welding for trailing arc were combined for tandem welding without any synchronization for cost effectiveness. Spatter generation and droplet transfer were observed for various inter-wire distances, leading currents and trailing currents. The spatters were mainly generated from the droplets on the leading electrode. Two mechanisms for spatter generation were explained from high speed images. The droplet was deflected by the trailing arc and could not be transferred into the weld pool. The instant short circuiting of streaming mode droplet was another cause of the spatter generation. Adequate inter-wire distances and current ranges for leading and trailing electrodes were suggested to suppress spatter generation.
Al/Fe 셀프피어싱 리벳 접합부의 부식특성 및 파괴거동
강상훈(Sanghoon Kang),윤진영(Jin Young Yoon),김철희(Cheolhee Kim) 대한용접·접합학회 2018 대한용접·접합학회지 Vol.36 No.3
In the automotive industry, light-weighting of chassis and car body is an inevitable trend to meet the fuel efficiency regulation. Therefore, the use of Al alloy is increasing and also joining with the conventional steel sheets is getting an important issue. The SPR(self-piercing rivet) joining kinds of mechanical fastening is preferred in Al/Fe joint due to different material properties between the Al and steel as like melting temperature, heat conduction coefficient and thermal expansion coefficient. However galvanic corrosion between rivet and materials is still a big issue to be solved in the SPR joint. In this study, salt spray test (SST) was performed for Al/Fe SPR joint in which 1 mm-thick of Al 6014-T4 and 1.2 mm-thick of GA 590DP steel sheets were joined with PFZn-Ni5L-B coated SPR. The steel sheet was electro-deposition coated prior to the SPR process. In SST up to 80 days, bearing load for tensile-shear test increased with increasing of exposure time, and fracture mode was not varied within the experimental period.